The present invention relates to a disk brake which is advantageously used for applying a braking force to, for example, a vehicle.
As a conventional disk brake, there has been known a disk brake comprising: a carrier including a pair of arms spaced from each other in the circumferential direction of a disk and axially extending across an outer circumference of the disk, each of the arms having a projecting pad guide; a caliper; a pair of friction pads adapted to be pressed against both surfaces of the disk by the caliper and each having recesses fitted onto the pad guides of the carrier; and a pair of pad springs, respectively, mounted on the pad guides of the carrier and resiliently pressing against the friction pads to thereby stably hold the friction pads between the pad guides of the carrier.
In the above-mentioned disk brake, when the brake is operated, a piston in a cylinder provided in the caliper on an inner side of the disk is caused to slide toward the disk in response to fluid pressure applied from the outside, so that the friction pads are pressed against the inner and outer surfaces of the disk between the piston and an outer side of the caliper, to thereby apply a braking force to the disk. In this instance, a braking torque acting on the friction pads is transmitted from the recesses of the friction pads to the pad guides of the carrier.
Each of the pad springs mounted on the pad guides of the carrier is made of, for example, a stainless steel plate. Each pad spring has integrally formed therewith a generally U-shaped guide plate which is bent along the corresponding pad guide of the carrier on which the pad spring is mounted. The guide plate is resiliently engaged with and presses against the corresponding pad guide of the carrier, so that the pad spring can be surely held in position, relative to the carrier.
Since the guide plate of each pad spring is positioned between the corresponding pad guide of the carrier and the friction pad, there is no disadvantage such that when the braking torque acting on the friction pad is transmitted to the pad guide of the carrier during operation of the brake, the friction pad, which includes a backing plate made of, for example, hot-rolled sheet steel, is likely to form an impression on the pad guide of the carrier, which is made of cast iron. In addition, due to the guide plate being positioned between the corresponding pad guide of the carrier and the friction pad, a lowering of slidability of the friction pad during operation of the brake, which is caused by adhesion of the friction pad to the pad guide due to rust accumulating on the backing plate of the friction pad and the pad guide, is suppressed, so as to prevent the occurrence of "drag" after operation of the brake.
In order to suppress a lowering of slidability of the friction pad during operation of the brake due to rust accumulating on the backing plate of the friction pad and the pad guide, there is provided a clearance between the guide plate of each pad spring, which is mounted on the pad guide of the carrier which receives a braking torque from the friction pad, and the recess of the friction pad which is fitted onto the pad guide. In order to prevent the friction pad from generating noise during operation of the brake, such as rattling and clonk noise, the size of the above-mentioned clearance between the guide plate of the pad spring and the recess of the friction pad is set to a size as small as, for example, 0.1 to 0.9 mm.
However, in the above-mentioned conventional disk brake in which the guide plate of each pad spring is resiliently engaged with and presses against the corresponding pad guide of the carrier, when the guide plate, and hence the pad spring, is mounted on the pad guide, a bent portion of the generally U-shaped guide plate is separated from a corner portion of the projecting pad guide and deformed into a projection in a circumferential direction of the disk toward the recess of the friction pad which is fitted onto the pad guide (as shown in FIG. 4). On the other hand, as mentioned above, the size of the clearance between the guide plate of each pad spring, which is mounted on the pad guide of the carrier, and the recess of the friction pad which is fitted onto the pad guide must be small, in order to prevent the friction pad from generating noise during operation of the brake. As a result, when fitting the recess of the friction pad onto the pad guide of the carrier with the guide plate of the pad spring being disposed therebetween, a problemd arises, such that the bent portion of the guide plate of the pad spring which is deformed into a projection at a corner portion of the pad guide interferes with the recess of the friction pad, whereby a time-consuming and cumbersome operation is required for mounting the friction pad on the carrier, thereby lowering operability.
Further, when the friction pad is forcibly mounted on the carrier regardless of the above-mentioned interference of the bent portion of the guide plate with the recess of the friction pad, a problem arises, such that the bent portion of the guide plate is brought into frictional contact with (interferes with) the recess of the friction pad, whereby slidability of the recess of the friction pad relative to the guide plate becomes low, leading to the occurrence of "drag" after operation of the brake.